Device for the optical-electrical scanning of an information carrier

ABSTRACT

A device for the optical-electrical scanning of an information carrier with a scanning device especially for use with a knitting machine having at least one lamp, at least one photoelectric cell, a transport means for establishing relative motion between the information carrier and the scanning device, including a control circuit to maintain a preselectable rated intensity in said lamp, a voltage limiting circuit for the lamp voltage, a first time member associated with said voltage limiting circuit through which the lamp voltage during the switch-on process is at first limited to a value above the preselected lamp voltage and a preselected time span after the switch on process to nominal lamp voltage and that the transport means is activated after attainment of a rated intensity.

United States Patent [191 Gottschal DEVICE FORTHE OPTICAL-ELECTRICALSCANNING OF AN INFORMATION CARRIER Inventor:

[75] Gernot Gottschal, Boblingen,

Germany [73] Assignee: Firma Franz Morat GmbH,

Hessbruhlstrasse, Germany Filed: Aug. 20, 1971 Appl. No.: 173,374

[30] Foreign Application Priority Data Sept. 22, 1970 Germany i. P 20 41795.2

[52] US. Cl.....; 250/205 R [51] Int. Cl. G0lj 1/32 [58] Field of Search250/205, 206, 214, 250/219 D, 219 FR; 307/311; 315/149, 151,

References Cited UNITED STATES PATENTS 11/1964 Passmore 250/219 FRPrimary Examiner.lames W. Lawrence Assistant Examiner-D. C. NelmsAttorney-John Lezdey et a1.

[5 7] ABSTRACT A device for the optical-electrical scanning of aninformation carrier with a scanning device especially for use with aknitting machine having at least one lamp, at least one photoelectriccell, a transport means for establishing relative motion between theinformation carrier and the scanning device, including a control circuitto maintain a preselectable rated intensity in said lamp, a voltagelimiting circuit for the lamp voltage, a first time member associatedwith said voltage limiting circuit through which the lamp voltage duringthe switch-on process is at first limited to a value above thepreselected lamp voltage and a preselected time span after the switch onprocess to nominal lamp voltage and that the transport means isactivated after attainment of a rated intensity.

6 Claims, 4 Drawing Figures i9 Amplifier Ad sfz'n Membefl 35 J j 11C'anzrol C'z'r'cur'l i 7 %;552? 47 i i l ,{z'mift'ng Circa/if g I i 4837' Wu: 6 I i 49 Circuit i l 5.] l 54 I Time Memev'! L 64 A 55 g 67 r'lI A 53 i I I Mofar PMENTEU B 16 I973 SHEET 30F 4 FIG. 3

DEVICE FOR THE OPTICAL-ELECTRICAL SCANNING OF AN INFORMATION CARRIERBACKGROUND OF THE INVENTION This invention relates to the field ofoptical-electrical scanning devices for information carriers.

In using known scanning devices, the information carriers areconsiderably stressed thermally by the lamps in order to achieve a highdegree of scanning accuracy and speed. If the information carrier duringa scanning process is step by step or continually transported through acrack or opening located between the lamps and a photoelectric cell, theheat generated by the lamp is distributed over a larger surface on theinformation carrier. Especially in case of slow feeding speeds or incase of protracted idleness of the information carrier i.e. when theinformation carrier is at a standstill for a longer period of time theinformation carrier may be so greatly heated up that it will be damagedor permanently deformed. This is undesirable .because the informationcarrier is generally intended for multiple use.

To avoid this disadvantage, there is-a possibility of providing heatfilters which absorb a certain portion of the ultrared radiation of thelamp which is not required for scanning. Heat filters, however, entailthe disadvantage that they offer either incomplete heat protection orthat they require such a great increase in the lamp output, especiallyin connection with film strips as information carriers, that the lampslifetime is considerably reduced.

Another possibility of avoiding the above-mentioned disadvantageconsists in disconnecting the lamp when the information carrier is at astandstill. But this entails the disadvantage that the lamp is notimmediately ready for operation again when it is turned on againbecause, when the nominal voltage is applied, the rated intensity isattained only in, for example, 500 milliseconds, as a function of thedimensions of the filament. This disadvantage is particularly seriouswhen the information carrier is to be used for the automatic control ofa machine, for example, a knitting machine, whereby every marking of theinformation carrier, which is scanned produces a control signal whichactivates some member of the machine, for example, a needle selectiondevice on the knitting machine. If the information carrier in such acase is to be adjusted step by step to a very specific marking from thestandstill several times very briefly by activating a switch so that acontrol processassociated with it can be controlled on the machine, thena time member would have to be connected with the switch in order to setthe information carrier in motion only at a delay of about 500milliseconds.

Such a delay in any switch activation is not desirable for the operatingpersonnel because during adjustment or during the repair and maintenanceof the machine it is very frequently necessary to adjust for a certainmarking.

OBJECTS OF THE INVENTION An object of this invention'is to create ascanning device by means of which, on the one hand, it is possible toprevent the excessive heating of the information carrier in a simplemanner and, on the other hand, which will permit the fastest possiblestart of the scanning of the information carrier.

A further object of this invention is to provide a scanning device whichcan be used at slow feeding speeds or when the information carrier is ata standstill for a long period of time.

It is a still further object of this invention to provide a scanningdevice for use in connection with a knitting machine which can havegreater start in a scanning operation.

SUMMARY OF THE INVENTION The present invention relates to anoptical-electrical scanning device. More particularly, this inventionrelates to an optical-electrical scanning device for use in connectionwith knitting machines.

This invention relates to a device for the opticalelectrical scanning ofan information carrier with a scanning device consisting of lamp meansand photoelectric cells, a feeder means to establish a relative movementbetween the information carrier and the scanning device, a controlcircuit to maintain a preselectable rated intensity of the lamps in thelamp means, and a limiting circuit for the lamp voltage.

In the device-of this invention there is a time member associated with avoltage limiting circuit and through the time member a lamp voltage isat first limited to a value essentially above the nominal voltage and toa preselected span of time after adjusting for the nominal voltage and apreselected span of time and after the switch-on process for the nominalvoltage. The feeder device begins to operate only after the ratedintensity has been attained.

The automatic limitation of the lamp voltage to a.

smaller value after the expiration of a certain span of time offers theadvantage that a destruction of the lamp can reliably be prevented evenif the nominal intensity is not attained because of some disturbance orif it is attained but not indicated.

Switching the maximum voltage from a high value to a smaller value,which generally corresponds to the nominal voltage of the lamp, istherefore a process which is controlled by a time member which isactivated by means of the switch-on process and which reliably switchesprior to the moment at which the lamp would be destroyed if it were tobe further overloaded.

According to a preferred further development of the invention, the ratedintensity of the lamp is maintained, during the disconnection or cutoffprocess up till the final termination of the scanning. If the scanningis accomplished by moving the information carrier .with're-'v lation tothe scanning device then the end of the scanning is attained and not,when the transport device of the information carrier is turned off butonly when the information carrier finally comes to a standstill. The

lamp must be kept at its rated intensity up to that mo- BRIEFDESCRIPTION OF THE DRAWINGS V A FIG. 1 is a schematic diagram of anoptical-electrical scanning device for an information carrier suitableto control a circular knitting machine;

The invention offers three essential advantages. This FIG. 2 is aschematic diagram of a switching circuit according to the invention forthe operation of the lamp and the feeder device for the informationcarrier of FIG. 1;

FIG. 3 is a schematic diagram of the time curve of the intensity, thecurrent, and the voltage of the lamp of the scanning device, and

FIG. 4 shows an example of the control circuit and the limiting circuitsof the switching circuit of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, the needle cylinder1 of a circular knitting machine, which can be rotated in the directionof the arrow, is illustrated schematically. The remaining parts of acircular knitting machine are known and are not necessary for theunderstanding of the invention. Cylinder needles 3, which may be movedup and down independently of each other, are arranged on needlecylinder 1. To select those cylinder needles 3, which may or may not beinvolved in the knitting process, there is provided control magnetsystems 5 which have electrical control signals via a line 19. Thecontrol signals are received through the scanning of an informationcarrier 7 which by means of transport rollers 9 is transported past ascanning device 11. The information carrier, for example, is a filmstrip with opaque and translucent markings. The scanning device 1 1contains at least one lamp 13 which, for example, can be an incandescentlamp, and at least one photoelectric cell (not shown). The electricalsignals obtained through scanning are fed to an electronic system 17and, after amplification and standardization, are fed to a pertinentcontrol magnet system 5.

A stepping motor 21 is used to drive the transport rollers 9, whereby atransmission or reduction gear 23 can be provided between the steppingmotor 21 and the transport rollers 9. The stepping motor is connectedvia lines 25, the electronic system 17, and a line 27, with a timingimpulse generator 29 which when the needle cylinder is rotated generatesone cycle signal per needle moving past and through this signal theinformation carrier 7 is transported further one step at a time.

As illustrated in FIG. 2, lamp 13 is connected to a battery 35 via aresistance 31 and an adjusting member 33. By means of adjusting member33, the output supplied to lamp 13 can be adjusted to any desired value.A photoelectric sensor 37 is used to determine the actual intensity oflamp 37 and gives an electrical signal which is proportional to theintensity which is supplied in an amplified manner to an amplifier 39and which is then supplied to a comparison circuit 41. In the comparisoncircuit the electrical signal is compared with a signal which isproportional to a preselected rated intensity and which is supplied viaa line 43. The difference between the signals that are proportional tothe actual intensity and the rated intensity is fed into a con! trolcircuit 45 which gives off a difference signal which is proportional tothis difference and which is amplified and then fed to an adjustingmember 33. As a function of the size of the difference signal, theadjusting member 33 is then adjusted in the correct direction until thedifference signal disappears or until lamp 13 has attained the desiredrated intensity.

To limit the lamp current, there may be used a limiting circuit 47. Thecurrent which flows through lamp 13 is measured on a resistance 31. Themeasurement signal is supplied to the limiting circuit 47 via a line 48.A signal is supplied to another input of the limiting circuit 47 via aline 49 and this signal represents a maximum permissible lamp current 1As long as the actual value of the lamp current is below the value I thelimiting circuit 47 have no influence on the remaining circuitarrangement.

However, if the actual value of the lamp current exceeds the value Ithen the limiting circuit 47 gives off a signal which activates aswitching member located in the control circuit 45 in such a manner thatthe difference signal given off by the control circuit 45 will remainlimited to the value which just happens to be present at the moment. Asa result, the adjusting member 33 remains in its momentary position andthe lamp current constantly retains the value l even if the ratedintensity of the lamp has not yet been attained.

The voltage applied to lamp 13 is limited by a limiting circuit 50. Thelimiting circuit 50 is supplied on the one hand, via a line 51, with thesignals proportional to the actual voltage and, on the other hand, via aline 52, with signals which are in a relationship with a preselectedmaximum lamp voltage U In case the actual voltage of lamp 13 is greaterthan U the limiting circuit 50 gives off a signal which is supplied tothe control circuit 45 and which causes the difference signal, appearingat the output of the control circuit 45, to remain constant, regardlessof the actual intensity of the lamp which just happens to be there atthat time, so long as the actual voltage of lamp 13 is greater than nwr-According to one preferred version of the invention, the maximum lampvoltage U can be selected differently. For this purpose there may beused a turn-on and tum-off switch 53 which is connected with a switch 55by means of a time member 54. The switch S5 is connected, on the onehand, to the line 52 and, on the other hand, to a point 59. The line 52is furthermore connected with a point 61. Point 59 is on a relativelyhigh potential U whereas point 61 is on a relatively low potential U forexample, the nominal voltage. Time member 54 is so designed that theswitch 55 is likewise closed when the turn-on and the turn-off switch 53is closed but it is opened again after a certain time delay. As a resultthe line 52, immediately after the turn-on process, is at first at arelatively high and then at a relatively low potential. X

With the turn-on and turn-off switch 53 there is furthermore connected aswitching member 63 through which a motor 65 is turned on at the momentof switchon and this motor brings about rotation of the needle cylinder1 of a circular knitting machine and thus a rotation of the transportrollers 9 of the information carrier 7.

If desired there may be further connected between line 52 and point 61another switch 57 upon which acts a second time member 67. Thecombination from switch 57 and time member 67 have the effect that theline 52 remains connected with point 61 for a preselected period of timewhen the turn-on and turn-off switch 53 is opened. Time member 67however does not prevent the immediate closing of switch 57 during theswitch-on process.

Line 52, connected with switches 55 and 57, is also directed with apoint 69 which is on a lower potential U when compared to points 59 and61.

As seen in FIG. 3, the device operates in the following manner:

Shown above each other is the time curve of the actual values of thelamp voltage U, the lamp current I, the lamp intensity (it and the speedV of the drive device 65. Furthermore, the particular values of U and Iare shown here in a broken line. Before a moment t the lamp voltage andthe lamp current are at a relatively small value which is determined viathe limiting circuit 50 through the potential of point 69. Point 69 isat this time at a potential U which corresponds to the resting state,that is, the standstill of the information carrier 7 and the needlecylinder 1. In this time interval, the rated intensity of lamp 13 cannotbe attained in spite of the fact that in the comparison circuit 41 agreat difference between the actual intensity and the rated intensity isobserved.

The maximum voltage U which is adjusted prior to the moment t can beabout 30 percent of the nominal voltage or less. It makes certain thatthe information carrier will not be damaged with the pertinent intensityof filament temperature of the lamp 13 even in case of longerstandstill.

The activation of the turn-on and turn-off switch 51 at moment t causesthe maximum voltage to be switched through switch 55 from the value U toa very high value U of point 59. Consequently, the control circuitbegins to work due to the absence of any voltage limitation as a resultof which the actual intensity of the lamp according to FIG. 3 increases.After a very short turn-on moment, however, the lamp current attains themaximum value I because the lamp resistance during switch-on isrelatively small so that shortly after switch-on the limiting circuit 47becomes effective for the lamp current. Thereafter, the actual intensityof the lamp increases while the current is constant and the lamp voltagerises slowly until it reaches the preselected rated value at time t,.After reaching the rated intensity, the lamp voltage and the lampcurrent drop due to the action of the control circuit down to relativelysmall values which are required to maintainthe rated intensity.

The value for U between moments t to t must be so selected that the lampwill under no circumstances be destroyed when these values are attained.In general, it is possible to select the two values between t and tconsiderably higher than the nominal values without the lamp beingdamaged even when the switch on process is repeated frequently.

By means of special circumstances, for example, con

tamination, it may happen thatthe lamp intensity does not attain theprescribed rated value even if an output considerably above the ratedoutput is supplied to the lamp beyond moment i One can also visualize acase in which the photoelectric cell 37 is swung put of the area of lamp113 sothat the control circuit45 cannot operate. In such cases, the lamp13 would be destroyed at some time after due to overload. To preventthis, time member 54 is so adjusted that after a certain delay which inFIG. 3 corresponds to the time interval between t, and t there willoccur a voltage limitation brought about through point 61. For thispurpose, point 61 is normally put on a potential U corresponding to thenominal voltage of the lamp, whereas time t is so selected that the lamp13 at time i, cannot yet be destroyed with certainty if during the timeinterval t to t it is supplied with an output computed from the possiblemaximum values U and 1 The switching member 63 which is activated byswitching on the turn-on and the turn-off switch 51 may have a differingfunction which depends on the inertia of the movable parts involved. Inthe example illustrated, when one is dealing with a circular knittingmachine with a relatively heavy needle cylinder 1, the needle cylinder 1and thus the information carrier 7 are not immediately set in motionduring the switch-on of the turn-on and turn-off switch 53. Instead, themovement of these parts begins only after an accidental delay time ofabout 70 milliseconds which, in FIG. 3, is illustrated through the timeinterval between t and t and which depends on the inertia of the system,torsion phenomena in the drive means, etc. In such a case, the switchingmember 63 can simultaneously with the switch-on process also turn on themotor 65 if steps have been taken to make sure that the time intervalbetween t and t within which the rated intensity of lamp I3 is normallyattained, is smaller than the time interval between t and 13 Since thetime interval t to t in the normal case, is only 30 milliseconds, it isnot necessary to provide any additional means for turning on the motor65.

The switching member 63 may be any switch such as an electronic switchwhich switches on the machine immediately upon operation of the switch53 or an electronic switch such as is known in the art.

Except for the case that the motor 65 and the parts connected with it,among other things, also the transport rollers 9 of information carrier7, can be set in motion within a time interval which is smaller than thetime interval between t and t steps must be taken to make sure that themotor 65 will beginto run only with a certain delay. This can. beachieved by associating with the switching member 63 a time member whichdelays the turn-on of the motor 65 until time t has been reached withcertainty. Another possibility, indicated in FIG. 2, consistsinactivating the switching member 63 not through the turn-on andturn-off switch 53 but rather to connect it via a line 64 with theoutput of the comparison circuit 41 so that it will always be activatedwhen the signal, appearing at the output of the comparison switch 41,has the value zero. In this way,- the motor 65 is turned on only whenthe rated intensity of lamp 13 is attained. v During the turn-offoperation, that is, during the opening of the turn-onand turn-off switch53 at time the rated intensity of thelamp is stillmaintained for acertain delay time which is determined by the timemember 67 up to a timeit and only then is the lamp voltage limited in accordance with thevoltage U This time delay during the turn-off process is necessaryinorder to make sure that the rated intensity will remain-- preserved atleast until, in the example selected, the needle cylinder 1 of thecircular knitting machine and thus the informationcarrier7 have come toa standstill at t,. The delay time brought about bythe time member itsother connection via a resistance 73 to the negative pole 75 of avoltage source. The connection point between the photoresistance 37 andresistance 73 is placed via a diode at the output 79 of the controlcircuit. During the switch-on process, that is, at time t,,, thephotoresistance is only weakly illuminated so that it has a highresistance and so that at output 79 there will be a potential whichroughly corresponds to the potential of pole 75.

In case of stronger illumination of photoresistance 37, the potential ofthe output 79 moves closer and closer to the zero potential. The signalappearing at output 79 is thus proportional to the difference betweenthe actual intensity and the rated intensity of lamp 13 and it can befed to the adjusting member 33 directly or via amplifiers and the like.1

For voltage limitation, there may be provided as shown in FIG. 4 atransistor 81 whose base is controlled by the actual value of the lampvoltage, whose collector is located at output 79, and whose emitter isconnected to a voltage divider which is located between pole 75 of thevoltage source and the ground and which is made up of resistances 83,85. The dimensioning of this limiting circuit is so selected that thetransistor 81 will always be connected through when the actual value ofthe lamp voltage exceeds a certain value that depends on the emittervoltage of the transistor 81 and thus the signal appearing at output 79is kept constant, even if the rated intensity has not yet been achieved.The switching to various throughconnection points of the transistor 81,corresponding to the various maximum voltages U U U (see also FIGS. 2and 3), can be accomplished by means of the correspondingswitches andresistances 87, 88 which are connected parallel to the resistance 83.

Finally, there may be provided a transistor whose emitter is groundedand whose collector is at output 79. Between output 79 and pole 75 ofthe voltage source there is the resistance 91. The base of transistor 89is controlled by a signal analogous to the actual value of thelamp'current. Transistor 89 is always connected through when the actualvalue of the current exceeds a preselected value, as a result of whichthe signal at output 79 is kept constant, even if the rated intensity isstill not achieved and if therefore a higher lamp output would berequired.

The invention is not confined to the examples described here. Inparticular it is immaterial at what point in the circuit diagram andwith whatmeans the voltage and current limitation are accomplished. Forexample, it would also be possible to bring about a limitation of thesevalues by simulating when the voltage or current boundary is reached anapparent attainment of the rated intensity, that is, upon attainment ofthe maximum voltage of the maximul current, it vwould be possible tofeed the comparison circuit 41 a changed rated value which would causethe difference signal to disappear and which would prevent any furthervoltage or current increase.

The invention is likewise not confined to circular knitting machinesinstead, it may advantageously be carried out where ever at thebeginning of the information carrier transport full lamp intensity mustbe achieved and must thereafter be maintained.

The individual switching elements of the control circuit, of thelimiting circuits, the time members, and the comparison circuit areknown and do not require any further explanation. The same applies toadjusting member 33 which, for example, can be a potentiometer or apower transistor driven by a motor.

Obviously the embodiments shown is exemplary only and a wide variety ofembodiments may be devised without departing from the spirit and scopethereof.

What is claimed is:

1. A device for the optical-electrical scanning of an informationcarrier, said device comprising: a scanning means having at least onelamp for scanning said information carrier; an automatic controllingsystem for maintaining a desired intensity of said lamp, saidcontrolling system having a photoelectric cell for sensing the actualintensity of said lamp, comparator means for comparing said actualintensity of said lamp with said desired intensity and a controllingmeans for controlling said lamp so that said actual intensity doescorrespond to said desired intensity during scanning operations;transport means for establishing relative motion between saidinformation carrier and said lamp for scanning operations; a switchingmeans for switching on and off said lamp and said transport means; avoltage limiting circuit for limiting the lamp voltage, and a firsttiming element means associated with said voltage limiting circuit forlimiting said lamp voltage when switching on said switching means atfirst to a value above a preselected rated voltage and a preselectedtime interval after said switch-on process to said rated lamp voltage.

2. The device according to claim 1, including a second timing elementassociated with said voltage limiting circuit for maintaining saiddesired intensity of said lamp a preselected time interval aferswitching off said switching means.

3. The device according to claim 2, wherein said voltage limiting meansincludes means for limiting said lamp voltage-to a resting voltage aftera delay determined by said second timing element whereby said restingvoltage corresponds to the voltage when the information carrier is at astandstill.

4. The device according to claim 1, including a current limiting circuitassociated with said lamp, said circuit acting when said informationcarrier is at a standstill and during scanning operations.

5. The device according to claim 1 including means coupled with saidswitchingmeans for automatically switching on said transport means afterattainment of said desired lamp voltage.v

6.The device according to claim 5, wherein said means for automaticallyswitching on said transport means is controlled by said comparatormeans.

1. A device for the optical-electrical scanning of an informationcarrier, said device comprising: a scanning means having at least onelamp for scanning said information carrier; an automatic controllingsystem for maintaining a desired intensity of said lamp, saidcontrolling system having a photoelectric cell for sensing the actualintensity of said lamp, comparator means for comparing said actualintensity of said lamp with said desired intensity and a controllingmeans for controlling said lamp so that said actual intensity doescorrespond to said desired intensity during scanning operations;transport means for establishing relative motion between saidinformation carrier and said lamp for scanning operations; a switchingmeans for switching on and off said lamp and said transport means; avoltage limiting circuit for limiting the lamp voltage, and a firsttiming element means associated with said voltage limiting circuit forlimiting said lamp voltage when switching on said switching means atfirst to a value above a preselected rated voltage and a preselectedtime interval after said switch-on process to said rated lamp voltage.2. The device according to claim 1, including a second timing elementassociated with said voltage limiting circuit for maintaining saiddesired intensity of said lamp a preselected time interval aferswitching off said switching means.
 3. The device according to claim 2,wherein said voltage limiting means includes means for limiting saidlamp voltage to a resting voltage after a delay determined by saidsecond timing element whereby said resting voltage corresponds to thevoltage when the information carrier is at a standstill.
 4. The deviceaccording to claim 1, including a current limiting circuit associatedwith said lamp, said circuit acting when said information carrier is ata standstill and during scanning operations.
 5. The device according toclaim 1 including means coupled with said switching means forautoMatically switching on said transport means after attainment of saiddesired lamp voltage.
 6. The device according to claim 5, wherein saidmeans for automatically switching on said transport means is controlledby said comparator means.